Analysis of Iran’s northern forests structure using the nearest neighbor indices (Case study: Dashtenaz forest protected area in Mazandaran province)

The first step in proper management of forests is having enough information about growth, development and how the forest stands structure are influenced by environmental factors. Considering the importance of forest stands in the north country and environmental values of the study area, structure of the existing species in Dashtenaz forest protected area in Mazandaran province has been investigated using the nearest neighbor indices. To investigate the structure of the study area, 56 hectare of the forest stands were statistically analyzed, and Clark and Evanes, Uniform angles, Shannon-Wiener, Mingling, DBH dominance and DBH differentiation indices were used to investigate the structure. The results showed that the mean Clark and Evans and uniform angles indices were 0.70 and 0.55 respectively, indicating a distribution between random and cluster patterns. Mean indices of Shannon-Weiner and Mingling were 0.40 and 0.06 respectively. Knowing that the study area is mostly composed of oak, the Mingling index value was calculated to be low​​. The mean DBH dominance index was calculated as 0.50, indicating the dominance of DBH of Quercus Castaneifolia and recessivity ofUlmus Glabra. Zelkova Carpinifolia was medium in terms of DBH dimension. Also average DBH differentiation index was calculated as 0.32, representing a medium difference between the trees next to each other in terms of DBH dimension. The indices used in this study can be used to describe the structure and ecological property of different species of trees.